The eye is a complex organ comprised of many parts that enable the process of sight. Vision quality depends on the condition of each individual part and the ability of these parts to work together. For example, vision may be affected by conditions that affect the lens (e.g., cataracts), retina (e.g., CMV retinitis), or the macula (e.g., macular degeneration). Topical and systemic drug formulations have been developed to treat these and other ocular conditions, but each has its drawbacks. For example, topical therapies that are applied on the surface of the eye typically possess short residence times due to tear flow that washes them out of the eye. Furthermore, delivery of drugs into the eye is limited due to the natural barrier presented by the cornea and sclera, and additional structures if the intended target resides within the posterior chamber. With respect to systemic treatments, high doses of drug are often required in order to obtain therapeutic levels within the eye, which increases the risk of adverse side-effects.
Alternatively, intravitreal injections have been performed to locally deliver pharmaceutical formulations into the eye. The use of intravitreal injections has become more common due to the increased availability of anti-vascular endothelial growth factor agents for the treatment of acute macular degeneration (AMO). Agents approved by the FDA for intravitreal injection to treat AMD include ranibizumab (Lucentis®: Genentech, South San Francisco, Calif.) and pegaptanib sodium (Macugen®: Eyetech Pharmaceuticals, New York, N.Y.). In addition, intravitreal bevacizumab (Avastin®: Genentech, South San Francisco, Calif.) has been widely used in an off-label application to treat choroidal neovascularization. Increased interest in developing new drugs for delivery directly into the vitreous for the treatment of macular edema, retinal vein occlusion, and vitreous hemorrhage also exists.
Currently, commercially available intravitreal injection devices lack many features that are useful in exposing the site of injection, stabilizing the device against the sclera, and/or controlling the angle and depth of injection. Many of the devices described in the patent literature, e.g., WO 2008/084064 and U.S. 2007/0005016, are also part of multi-component systems that are generally time consuming to set up and use. The increased procedure time associated with these devices may in turn increase the risk of complications. Further, having to manipulate many components by itself may increase the risk of complications due to user error. A serious complication of intraocular injection is intraocular infection, termed endophthalmitis that occurs due to the introduction of pathogenic organisms such as bacteria from the ocular surface into the intraocular environment, or trauma to the ocular surface tissues such as corneal or conjunctival abrasion.
Accordingly, new devices for performing intravitreal injections would be desirable. Ergonomic devices that simplify the injection procedure and reduce the risk of complications would be useful. Devices that accurately and atraumatically inject drugs, e.g., liquid, semisolid, or suspension-based drugs, into the eye would also be useful.